Properly insulating structures such as buildings and homes continues to gain in importance especially in view of rising energy costs. One of the most common ways to insulate buildings and homes is to install batts of fiberglass or blown fiberglass insulation around the exterior walls of the structure. For example, fiberglass insulation materials are typically used to insulate attics, crawl spaces, and vertical wall cavities. Such materials have been found well suited to preventing heat from escaping from the insulated area in colder months and cool air from escaping from the area in hotter months.
Although fiberglass insulation materials have very desirable R-values in static conditions, the thermal performance of the materials significantly decreases when subjected to air flow. Thus, in the past, builders have applied a spray foam material, such as a polyurethane foam, to a surface to be insulated prior to installing fiberglass insulation. The rigid polyurethane foam has been found to serve as an effective air flow barrier while also providing other beneficial insulation characteristics.
The polyurethane foams are typically formed on site by mixing a polyol with an isocyanate. Isocyanates used in the past have typically comprised aromatic isocyanates, such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI). Specifically, in order to form a foam, the isocyanate component is combined with a polyol in the presence of a blowing agent and sprayed out of a nozzle onto the surface to be treated.
One of the disadvantages to using a ridged polyurethane foam as an air barrier is that the material is prone to crack or pull away from the surface being insulated either at the time the foam is installed or years later as the structure or building moves or settles. Air infiltration can occur where the foam has cracked or pulled away from the surface, thus negating some of the original benefits of installing the foam.
In view of the above, a need currently exists for an improved insulation system including an air barrier that does not crack or pull away from the surface being insulated.